Previous analysis of the teleseismic data recorded by the 41-station seismic
array in the Santa Clara Valley (SCV) (Dolenc et al., 2005) showed strong
correlations between basin depth reported in the USGS 3D seismic velocity
model (ver. 2) (Jachens et al., 1997) and different relative measures of
ground motion parameters such as teleseismic arrival delays, P-wave amplitudes,
and wave energy. The results suggested that the teleseismic dataset is
sensitive to the basin structure and could therefore be used to improve the
3D velocity model.

We used teleseismic waveforms recorded by the SCV seismic array in an
inversion to refine
the USGS v2 model velocity structure within the SCV basins. To reduce the
extremely large model space, we inverted only for the velocity structure
within the basins while the basin geometry, as defined in the USGS v2 velocity
model, was held fixed. The P- and S-wave velocities, and density in
the basins were modeled as laterally uniform and with vertical gradients.
The minimum S-wave velocity included in the model was 1 km/s.